Absent embodiments of the present invention, devices need to use the home network that they are associated with to access services in an IMS environment. This is inefficient when customers are geographically or communicatively distant from their home network, but within a closer proximity to another carrier's network. For example, a U.S. customer visiting China may have to have his call backhauled to the U.S. to access various service offerings. Moreover, current methods do not allow for embedding NAIs into a single string (and hence, require at least increased overhead and processing of multiple individual strings that each describe only a single NAI) nor extracting the same in an IMS setting.